1. Field of the Invention
The present invention relates to an electric motor which is provided for use in a dental, dental-medical or dental-technical handpiece, and a stator therefore. In particular the present invention relates to a so-called collectorless motor.
2. Related Technology
In dental, dental-medical or dental-technical handpieces treatment or working instruments are put into rotation or vibration with the aid of a drive. The drive may on the one hand be configured in the form of an air turbine or an air motor; alternatively to this also the use of electric motors has gained increased acceptance in recent times. Here there are put to use in particular so-called collectorless or brushless dc motors (BLDG motors), the rotor of which has at least one permanent magnet. Such motors stand out due to their high efficiency.
Difficulties in the use of such electric motors in the handpieces mentioned above consist, however, in that the handpieces must regularly be cleaned and sterilized for hygienic reasons. Sterilizing is normally effected in that the handpiece is exposed to an atmosphere with high humidity and high temperature, to kill organisms possibly present. However, precisely the combination from high atmospheric humidity and high temperature has the consequence that the sensitive components of an electric motor may be damaged. Here, particularly problematic are the functionally relevant components of the stator, that is for example the stator windings, the return plates and/or the contact pins, since here the penetration of hot steam can lead to corrosion and/or structural changes and can correspondingly damage the components.
To avoid damage to the electric motor in the context of the regular cleaning or sterilization, in the past handpieces were conceived in which the motor, in the form of a separate component, could be selectively put in place in the handpiece and removed again. Then for cleaning purposes the motor was initially removed and exclusively the handpiece sleeve cleaned. It was avoided in this way that the motor was repeatedly exposed to the high temperatures of sterilizing, so that the operating life thereof was extended. Of disadvantage with this concept is, however, that the motor is not arranged fixed in the handpiece housing with respect to the further elements of the power train, which during operation in particular at high rotational speeds can lead to problems. A precise transmission of motion from the motor to the treatment or operating tool is only then ensured when the motor is arranged fixedly and permanently within the handpiece. Further, a fixed arrangement of the motor in the handpiece would lead to a lighter and more compact manner of construction, which would improve the handling of the handpiece considerably for the user or dentist.